The popular swimming spots of Buley Rockhole, Florence Falls and the upper Cascades have been inundated with water from rainfall throughout the National Park, which is 100km south of Darwin.

On Sunday, 150mm fell in the Park between 9am and 3pm alone.

"We have closed the Upper Cascades, Florence Falls and Buley Rockhole to swimming as conditions have become unsafe due to the heavy rainfall over the last couple of days," park ranger Sean Webster said.

"The three designated swimming areas are currently flooded, which is causing strong currents, water clarity issues and unsafe conditions for swimming.

"Aida Creek is also experiencing flooding and may cause accessibility issues to visitors, please check flood markers before attempting to cross."

Ordinarily, Buley Rockhole and Florence Falls are the only two swimming holes in Litchfield National Park to remain open all year round.

Parks and Wildlife is urging the public to reschedule any plans to visit Litchfield National Park until the rain subsides and conditions become safe again.